If you want to use your 105 and send DSD to a DAC, look for a DAC that supports DSD and has i2s in. With my 203, I send the DSD via the HDMI 2 out to an inexpensive HDMI to i2s converter and connect the i2s to my DAC. This works beautifully and should work with your 105. I have not tried this on my 105, so can't verify for certain that it will work, but it should.
SACD over HDMI
I used an Oppo 105 and output DSD from SACD over HDMI into my Bryston DAC3, which has 4 HDMI inputs. Yesterday a power outage may have fried the Bryston. The current Bryston DACs removed HDMI.
My question is I ought to be able to replace it with any DAC that offers eARC with an HDMI input, correct? I’ve been doing this for 7 years now and have around 150 SACDs